Electric heater



Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE ELECTRIC HEATER Mich.

Application January 20, 1936, Serial No. 59,812

14 Claims.

This invention relates to electric heaters, and more particularly to fluid heaters of the induction type.

The objects of my invention are:

First, to provide an electric heating system which is highly efficient, automatic in operation, and very effective for the purpose intended.

Second, to provide a heating unit which may be used in a great variety of ways in both domestic and industrial systems.

I attain these objects by mechanism illustrated in the accompanying drawing in which The single figure is a diagrammatic representation of my heating system, the heating unit being shown in vertical section.

Referring to the drawing, my electric heating system comprises a heating unit I and a transformer 2. The transformer has a conventional primary winding 3 and a secondary winding path 20 4. The secondary winding path consists of a non-conducting conduit in the form of a coil as shown. W

The heating unit has a closed chamber provided with a conical bottom 5 containing the heating liquid, preferably mercury, the space 6 above the liquid providing room for the vaporization of the liquid when heated. Theheating unit is adapted to be placed so as to act upon air to be conditioned, or in any other system requiring the generation of heat.

An external pipe I connects the bottom of the closed chamber with the top thereof, the ends of the secondary coil being connected to the pipe below the normal liquid level of the mercury 8. Thus the liquid in the coil and pipe provides a closed circuit as long as the liquid remains above the juncture 9 at the top of the coil and the pipe.

The liquid circuit provides a current path resulting in the heating of the liquid by induction when the transformer is energized. The circuit is automatically opened when the heat induced in the circuit vaporizes the mercury to such an extent that the liquid level falls below the junction 9. The subsequent cooling and condensation of the mercury vapor raises the liquid level to again close the heating circuit. The vaporization and condensation of the mercury thus controls the opening and closing of the liquid circuit and maintains substantially constant the heat generated by the heating unit I.

The power supply to the primary winding 3 is controlled by temperature responsive means, such as a thermostat l0, disposed in the medium to be conditioned, in the present case air. The input circuit is also provided with normally closed pressure responsive means ll disposed in the closed chamber, said means acting to open the input circuit when the vapor in the chamber reaches a predetermined pressure. Excessive gas pressure within the chamber is thus prevented. 5

The normal level of the heating liquid within the closed chamber is indicated by the dotted line l2. This level falls due to the vaporization of the liquid until the liquid secondary circuit of the transformer is opened, as pointed out 10 above. The vapor provides an excellent medium for distributing the heat in the heating unit, the rise and fall of the heating liquid relative to the junction 9 keeping the heating unit automatically at a substantially constant temperature 15 while the transformer is energized.

It will be apparent to those skilled in the art of induction heating that I have provided a heating system which is very efficient and effective in operation, such operation being entirely auto- 20 matic by virtue of my unique use of the heating fluid as the secondary of a transformer when a liquid, and as a heat distributing medium when a gas. I prefer to use mercury because it is a good electrical conductor in the liquid state and 25 a good heat conductor in the gaseous state.

It should be noted here that the pressure within the closed chamber of the heating unit is preferably somewhat below atmospheric to improve the operating characteristics of the mercury.

I claim:

1. An electric heating system comprising a transformer having a primary winding and a secondary winding path, temperature responsive means acting to control the power supply to said 35 primary winding, the secondary winding path consisting of a non-conducting conduit in the form of a coil, a pipe connecting the ends of said coil, a heating unit having a closed chamber containing a fluid changeable from a liquid to a gas 40 when heated, the top and bottom of said chamber being in communication with said pipe, said fluid in its normally liquid state filling said coil and pipe to provide a closed circuit, the heating of the fluid resulting in the vaporization of the 5 liquid and the opening of said circuit, and pressure responsive means in said chamber acting to open the input circuit of said primary winding when the pressure therein reaches a predetermined amount.

2. An electric heating system comprising a transformer having a primary winding and a secondary winding path, temperature responsive means acting to control the power supply to said primary winding, the secondary winding path 55 consisting of a non-conducting conduit in the form of a coil, a pipe connecting the ends of said coil, a heating unit having a closed chamber containing a fluid changeable from a liquid to a gas when heated, the top and bottom of said chamber being in communication with said pipe, said fluid in its normally liquid state filling said coil and pipe to provide a closed circuit, the heating of the fluid resulting in the vaporization of the liquid and the opening of said circuit, and pressure responsive means in said chamber acting to open the input circuit of said primary winding when the pressure therein reaches a predetermined amount.

3. An electric heating system comprising a transformer having a primary winding and a secondary winding path, temperature responsive means acting to control the power supply to said primary winding, the secondary winding path consisting of a non-conducting conduit in the form of a coil, a pipe connecting the ends of said coil, and a heating unit having a closed chamber containing a fluid changeable from a liquid to a gas when heated, the top and bottom of said chamber being in communication with said pipe, said fluid in its normally liquid state filling said coil and pipe to provide a closed circuit, the heating of the fluid resulting in the vaporization of the liquid and the opening of said circuit.

4. An electric heating system comprising a transformer having a primary winding and a secondary winding path, the secondary winding consisting of a non-conducting conduit in the form of a coil, a pipe connecting the ends of said coil, and a heating unit having a. closed chamber containing a fluid changeable from a liquid to a gas when heated, the top and bottom of said chamber being in communication with said pipe, said fluid in its normally liquid state filling said coil and pipe to provide a closed circuit, the heating of the fluid resulting in the vaporization of the liquid and the opening of said circuit.

5. An electric heating system comprising a transformer having a primary winding and a secondary winding path, temperature responsive means acting to control the power supply to said primary winding, the secondary winding path consisting of a non-conducting conduit, a pipe connecting the ends of said conduit, a heating unit having a closed chamber containing a fluid changeable from a liquid to a gas when heated, the top and bottom of said chamber being in communication with said pipe, said fluid in its normally liquid state filling said conduit and pipe to provide a closed circuit, the heating of the fluid resulting in the vaporization of the liquid and the opening of said circuit, and pressure responsive means in said chamber acting to open the input circuit of said primary winding when the pressure therein reaches a predetermined amount.

6. An electric heating system comprising a transformer having a primary winding and a secondary winding path, the secondary winding path consisting of a non-conducting conduit, a pipe connecting the ends of said conduit, and a heating unit having a closed chamber containing a fluid changeable from a liquid to a gas when heated, the top and bottom of said chamber being in communication with said pipe, said fluid in its normally liquid state filling said conduit and pipe to provide a closed circuit, the heating of the fluid resulting in the vaporization of the liquid and the opening of said circuit.

7. An electric heater comprising a heating unit having a closed mercury chamber provided with a conical bottom containing liquid mercury, the space above the liquid mercury providing room for the vaporization of the mercury when heated, an external pipe connecting the bottom of said chamber with the top thereof, and a transformer having a secondary winding means consisting of a mercury conduit in the form of a non-conducting coil having its ends connected to said pipe below the normal liquid level of the mercury, the liquid mercury in said coil and pipe providing a closed circuit as long as the liquid mercury level remains above the junction of the top of said coil and said pipe, said circuit being automatically opened when the heat induced in the circuit vaporizes the mercury to such an extent that the liquid mercury level falls below said junction, the vaporization and condensation of the mercury thus controlling the opening and closing of the circuit and the heat generated by said heating unit.

8. An electric heater comprising a heating unit having a closed mercury chamber containing liquid mercury, the space above the liquid mercury providing room for the vaporization of the mercury when heated, an external pipe connecting the bottom of said chamber with the top thereof, and a transformer having a secondary winding means consisting of a mercury conduit in the form of a non-conducting coil having its ends connected to said pipe below the normal liquid level of the mercury, the liquid mercury in said coil and pipe providing a closed circuit as long as the liquid mercury level remains above the junction of the top of said coil and said pipe, said circuit being automatically opened when the heat induced in the circuit vaporizes the mercury to such an extent that the liquid mercury level falls below said junction, the vaporization and condensation of the mercury thus controlling the opening and closing of the circuit.

9. An electric heater comprising a heating unit having a closed mercury chamber provided with a conical bottom containing liquid mercury, the space above the liquid mercury providing room for the vaporization of the liquid mercury when heated, an external pipe connecting the bottom of said chamber with the top thereof, and a transformer having a secondary winding means consisting of a mercury conduit having its ends connected to said pipe below the normal level of the liquid mercury, the liquid mercury in said coil and pipe providing a closed circuit as long as the liquid mercury level remains above the junction of the top of said conduit and said pipe, said circuit being automatically opened when the heat induced in the circuit vaporizes the liquid mercury to such an extent that the liquid mercury level falls below said junction, the vaporization and condensation of the mercury fluid thus controlling the opening and closing of the circuit and the heat generated by said heating unit.

10. An electric heater comprising a heating unit having a closed chamber provided with a conical bottom containing liquid, the space above the liquid providing room for the vaporization of the liquid when heated, an external pipe connecting the bottom of said chamber with the top thereof, and a transformer having a secondary winding path consisting of a non-conducting conduit having its ends connected to said pipe below the normal level of the liquid, the liquid in said coil and pipe providing a closed circuit as long as the liquid level remains above the junction of the top of said conduit and said pipe, said circuit being automatically opened when the heat induced in the circuit vaporizes the liquid to such an extent that the liquid level falls below said junction, the vaporization and condensation of the fluid thus controlling the opening and closing of the circuit and the heat generated by said heating unit.

11. An electric heater comprising a heating unit having a closed mercury chamber provided with a conical bottom containing liquid mercury, the space above the liquid mercury providing room for the vaporization of the liquid mercury when heated, an external pipe connecting the bottom of said chamber with the top thereof, a conduit having its ends connected to said pipe below the normal liquid level of the mercury, the liquid mercury in said conduit and pipe providing a closed circuit as long as the liquid mercury level remains above the junction of the top of said coil and said pipe, and means acting to heat said circuit by induction, said circuit being automatically opened when the heat induced in the circuit vaporizes the liquid mercury to such an extent that the liquid mercury level falls below said junction, the vaporization and condensation of the mercury thus controlling the opening and closing of the circuit and the heat generated by said heating unit.

12. An electric heater comprising a heating unit having a closed chamber containing liquid, the space above the liquid providing room for the vaporization of the liquid when heated, an external pipe connecting the bottom of said chamber with the top thereof, a conduit having its ends connected to said pipe below the normal liquid level, the liquid in said conduit and pipe providing a closed circuit as long as the liquid level remains above the junction of the top of said coil and said pipe, and means acting to heat said circuit by induction, said circuit being automatically opened when the heat induced in the circuit vaporizes the liquid to such an extent that the liquid level falls below said junction.

13. An electric heating system comprising a closed chamber containing a liquid and having a space above the liquid for the vaporization thereof, an external conduit for the liquid providing a closed circuit as long as the liquid is above a certain level in the chamber, and means for inducing a current flow in said circuit toheat the liquid, the subsequent vaporization of the liquid resulting in the falling of the liquid below said level and the opening of said circuit, the opening of said circuit being followed by the cooling of the system and the condensation of the vapor which raises the liquid above said level and again closes the circuit, this cycle beingautomatically repeated during the operation of the system, said conduit and chamber being arranged to contain a substantial quantity of the liquid at all times.

14. An electric heating system comprising a closed chamber containing a liquid and having a space above the liquid for the vaporization thereof, an external conduit for the liquid providing a closed circuit as long as the liquid is above a certain level in the chamber, and means for inducing a current flow in said circuit to heat the liquid, the subsequent vaporization of the liquid resulting in the falling of the liquid below said level and the opening of said circuit, the opening of said circuit being followed by the cooling of the system and the condensation of the vapor which raises the liquid above said level and again closes the circuit, this cycle being automatically repeated during the operation of the system.

PETER A. CLAPP. 

